Understanding Hemifacial Microsomia (HFM) 

Hemifacial microsomia (HFM) is a condition that affects the form and shape of the bones and tissues of the face. The term hemifacial means one half of the face and microsomia means smallness. Your child’s face may look uneven, or the two sides may not look the same. This is because one side of the face is less developed. It most often affects the lower and upper jaws, cheekbone, eye, one side of the skull, ear, and some of the nerves that control movement of the face. In some cases, both sides may be affected. It is a congenital problem. This means that a child is born with it.

How to say it

Hem-ee-FAY-shul My-kro-SO-mee-uh

What causes HFM? 

HFM often happens by chance. The cause of HFM is uncertain. It can develop during pregnancy at around 4 weeks of a baby’s growth.

It may also run in some families. HFM may be passed on (inherited) through a faulty gene in these ways:

• Autosomal dominant. This means that only 1 parent passes the gene on to the child. Each child has a 1 in 2 chance of having the condition.

• Autosomal recessive. This means that both parents must have the gene to pass it on. Each child has a 1 in 4 chance of having HFM.

• Multifactorial. This means that many factors are involved. The factors are often genetic and external, such as injury during pregnancy. Genes, smoking, hormonal therapy, vascular injury, vasoactive medications, and cocaine use can cause this condition. So can maternal-fetal factors, such as maternal diabetes, hypothyroidism, and celiac disease.

This condition may also occur in children who have other chromosome problems. Chromosomes are the structures in our cells that carry our genes. These types of problems often occur by chance.

Symptoms of HFM 

Symptoms can occur a bit differently in each child. They may range from mild to severe. Areas on one side of the face may have less growth and be shaped differently, such as:

• Outside and middle of the ear:

  • Small nodules of excess skin around the ear.

  • Poorly developed or absent external ear.

  • Underdeveloped or absent structures of the middle and inner ear.

  • Hearing loss.

• Side of the skull: the forehead and cheek are flattened on the affected side.

• Bone around the eye: one eye socket is smaller than normal.

• Thickness of the cheek.

• Upper and lower jaws:

  • Underdeveloped upper and lower jaws on one side of the face.

  • Your child's mouth may appear to slant upward toward the affected side.

  • Appearance of a “crooked smile,”

  • Inability to chew.

• Teeth.

• Airway and feeding difficulties due to underdevelopment of the pharynx, larynx, esophagus, mandible, and chewing muscles.

The condition may also affect some of the nerves in the face. This can cause loss of sensation, weakness of muscles, and problems with moving parts of the face. In some cases, other parts of the body may also be affected by HFM. 

Diagnosing HFM 

A geneticist may diagnose HFM. This is a health care provider with extra training to diagnose and treat conditions passed down in families (genetic conditions). The health care provider will look at your child’s health history. They will give your child a physical exam. Your child may also have tests, such as:   

• X-rays of the head. X-rays use a small amount of radiation to show tissues and bones inside the body.

• CT scan. A CT scan uses a series of X-rays to show detailed images of the body. Your child may need a CT scan of the head. This test will show your child's bones, muscles, and other tissues. 

• Additional tests include an audiogram to evaluate hearing loss and perceptual speech analysis for speech development.

• Evaluation of chromosomes and genetic counseling can also be offered for families with suspected genetic inheritance.

Treatment for HFM 

Damage of everyday functions, such as airway obstruction and swallowing problems, would be treated first.

If your child has bad facial changes, they may need several surgeries. Reconstructive surgery for HFM has the goal of improving facial unity, jaw function, and normal alignment of teeth. In this case, your child will be checked by a craniofacial anomalies team. This is a group of health care providers who diagnose and treat problems of the face. 

This team may include:

• A craniofacial surgeon who can do jaw surgery and ear reconstruction.

• An ophthalmologist to diagnose and treat eye and vision issues.

• An orthodontist to check and treat jaw growth and position.

• An ear, nose, and throat health care provider (ENT or otolaryngologist) to check hearing loss.

• A speech therapist to help with speaking problems.

Your child’s treatment may include:

• Fixing your child’s lower jaw, using a bone graft taken from your child’s ribs.

• Using a device to change the shape of your child’s jaw.

• Surgeries to fix your child’s ear or cheeks.

• Removing or changing the position of your child’s teeth.

Possible complications of HFM 

If your child has mild facial changes, they may not be at risk for complications. Children with more severe changes may be more likely to have issues. These can include:

• Hearing loss.

• Eating problems.

• Trouble with self-image.

Helping your child live with HFM 

HFM support groups can help you and your child. Ask your child’s health care provider about support groups in your area.

When to call your child’s doctor 

Contact the health care provider if:

• Your child has trouble eating.

• Your child has trouble gaining weight.

• Other new problems occur in your child.